Aventon does not publish one error-code table. It publishes three, and they are split by drive architecture rather than by bike name or model year. Look a code up in the wrong table and you can spend money on a part that was never at fault.
Here is how the three are organized, the hub-drive codes you are most likely to meet, and the one decision in the official documents that saves the most money.
Three tables, split by architecture
The three sections are Hub Drive, ACU Hub Drive, and Mid Drive. ACU refers to bikes built around a smart control unit with connectivity hardware on board, and those carry codes the other two platforms do not have. Mid-drive bikes reuse most of the hub-drive numbering but add their own entries for the display and electronic shifting.
The format is unusually good for riders: one article per code, each with a diagnostic flow chart published as a PDF. That is closer to a service manual than most brands put in public.
The hub-drive codes you are most likely to see
E21, current error. The controller shut itself down after drawing more current than it permits, common on long climbs at maximum assist. Power off for about two minutes and restart, then inspect motor and controller cabling for chafing, dirt, or a loose plug. If it keeps returning, the motor or controller is failing.
E22, throttle error. Check that the throttle returns to rest cleanly and that nothing is jammed against it, then look for a nicked or crushed section of throttle cable. If neither turns anything up, the throttle assembly is the part to replace.
E23 and E24, motor phase and motor hall. The current documentation answers these with a flow chart rather than written steps. The older published guidance was to clean the motor connector and seat it firmly, and to contact support if the code survives that.
E25, brake sensor. Holding a brake lever while the bike powers up will trigger this on its own, and a restart clears it. If it persists, the sensor gap needs adjusting or the lever assembly needs replacing.
E26 and E27, overheat and motor lock. E26 asks you to stop and let the system cool, and it usually clears itself; if it appears on flat ground, that is worth reporting. E27 means the wheel is being held from turning, so check the rear wheel for something jammed in it, clear it, and restart.
E28 and E29, low and over voltage. For E28, charge to completion and try again. If it continues, the pack voltage needs measuring at a dealer, and a pack that will not reach its rated figure when charged is the part to replace. E29 points the other way, and the first thing to confirm is that the battery and charger are the ones the bike shipped with.
E30, E31, E41, E42 and E44. E30 is a controller-to-display communication failure: inspect every cable between the two, and if that changes nothing, the documented replacement order is display, then controller, then harness. E31 is battery communication on CAN systems. E41 points at the controller, E42 at the motor, and E44 at the torque sensor, and each begins with repairing the connection before any part is replaced.
The table also covers battery, lighting and charger-mismatch entries, plus W-prefixed warnings for throttle, thermal limits, motor lock, and out-of-date firmware. ACU adds control-unit communication, battery lock failures, geofencing, and connectivity warnings. Mid-drive adds a display fault code and electronic shifting entries.
About Error 04
People search for this one constantly, so it is worth being direct: we looked for an Aventon Error 04 across all three official tables and did not find it. If a two-digit 04 is on your screen, it is more likely coming from a display sourced elsewhere than from the Aventon code set. Two-digit tables from other display families do use 04, which is a good reason to identify your display before trusting any table.
The decision that saves the most money
This part is worth memorizing, and it applies beyond one brand. When pedal assist and the throttle are both dead, the shared component is the controller, and that is what the official guidance replaces. When only one of the two is dead, the fault is in that input: a dead throttle with working pedal assist means the throttle, and dead pedal assist with a working throttle means the cadence or torque sensor. Torque-sensor bikes should have the factory reset procedure run first, since a sensor that only needs recalibrating looks exactly like a failed one.
Two honest limits
These meanings come from the manufacturer help center, not from us, and they can change with firmware. If a printed manual came with your bike, that manual wins. And a code tells you which subsystem is complaining, never which part has failed, which is why every entry above starts with connectors and cabling before any replacement.
If your bike is not an Aventon, the numbering may still look familiar, because a family of brands share the same 21 through 30 block. We covered that overlap in the code family most brands share. For the wiring behind E23 and E24, see controller wiring color codes. And if you are chasing a dead pedal assist with no code at all, start here.